Both oxidative stress and ischemia-reperfusion injury, vhich are thought to be by superoxide (02-) have been proposed as etiologies of organ or vessel in sequelae of prematurity including intraventricular hemorrhage, retinopathy aturity, bronchopulmonary dysplasia and necrotizing enterocolitis. In almost all aerobic cells the primary defense against O2- is provided by the family of metalloenzymes called superoxide dismutases (SOD), including the manganese (Mn) SOD vhich is located predominantly in mitothondria. There is limited information about the regulation of these host defenses, and less about the defenses of premature infants developing in an oxygen rich environment ex-utero. We have found that there is tissue-specific MNSOD MRNA expression in humans and that human placenta expresses four different MNSOD transcripts. The purpose of this proposal is to define the molecular basis for tissue-specific expression of the human MNSOD gene in order to understand the regulation of MNSOD enzyme biosynthesis, processing, targeting and its role in cellular physiology and pathophysiology. This vill be approached by the hypothesis that MNSOD gene regulation and transcript formation is controlled by cis-regulatory sequences. Detailed expression of the MNSOD mRNAs vill be examined in a variety of tissues and in in vitro cell lines. A chimeric hGH-MnSOD gene will be constructed to allow detailed analysis of the cis-regulatory elements. The possible contribution of secondary structure or sites of regulatory interactions vith trans-acting factors vill be tested by directed deletional and autational analysis of potential cis-regulatory regions. Working on this project Dr. Church vill continue her development and training in molecular and cellular biology under the sponsorship of Dr. Colten vho has used ithese approaches for the study of the complement gene systems. The experiments are , expected to be greaily facilitated by an ongoing interaction vith Dr. Rick Wetzel and Dr. Arnold Strauss whose laboratory is studying the regulation and processing of other nuclear encoded mitochondrially directed proteins. The long range goal of this proposal vould be to identify and isolate potential trans-acting factors because they might be involved in co-ordinating cellular response to oxidant stress and might be important to the very premature infant.